This invention relates to a spark plug boot keeper assembly and more particularly to a spark plug boot keeper assembly for a combustion engine.
Spark plugs are known to have a male terminal protruding from a mid ceramic portion. An ignition wire terminal clip or female terminal press fits and thereby locks onto the male terminal of the spark plug. This high voltage electrical connection is surrounded by an elastomeric, electrically insulating, boot which is integral to the ignition wire and fits down snugly around the mid ceramic portion of the spark plug. In addition to the boot""s insulating characteristics it also assures that the high voltage electrical connection remains clean and free of moisture.
In today""s more complex combustion engines, the spark plug must be inserted into a deep spark plug well (typically surrounded by a heat dissipating head of an engine block) and then threaded into the spark plug hole in the head of the engine block. Since access to the spark plug within the well is limited and only the top of the spark plug is viewable, connection of the terminal clip inside the boot to the spark plug is cumbersome and visible inspection is difficult. The terminal clip must be made of a high strength electrically conductive metal in order to assure that the clip does not disengage from the spark plug thereby causing a rough running engine. The clip must be able to maintain its strength during vibrating engine conditions and after repeated engagement and disengagement""s of the ignition wire to the spark plug during engine maintenance. If the female terminal clip were to unseat from the spark plug a rough running engine would result and warranty costs would increase.
In addition, the collection of heat or hotspots within the spark plug well can cause damage to the most durable of elastomeric spark plug boots. A damaged boot can contribute to high voltage arching from the ignition wire to the engine block weakening the sparking characteristics of the spark plug. To help resolve this problem, heat shields are known to surround the boot, evenly distributing and dissipating the otherwise damaging heat. Unfortunately, the heat shields further narrow the spark plug wells making plugging of the ignition wire terminal onto the spark plug and the visible inspection of the spark plug connection all the more difficult.
The present invention provides a spark plug boot keeper assembly which ensures that a spark plug boot is properly installed in a deep well and locked onto a spark plug. The spark plug boot assembly has a pivoting member which engages to a lock face. The pivoting member and the lock face are interconnected between an internal surface of a spark plug well and a spark plug boot. The elongated spark plug well is preferably concentric about a centerline. The internal surface is defined by an upper wall, an upper shelf, a lower wall, and a bottom shelf. The upper wall extends downward to the upper shelf. The upper shelf is preferably annular, and extends radially inward to a lower wall. The lower wall extends downward to a bottom shelf which is annular in shape and defines an aperture through which the spark plug extends from an engine block along the centerline.
The spark plug boot has a circumferential lower rib which extends radially outward and engages the upper shelf when the boot is properly and fully seated with the spark plug. The pivoting member is disposed above the upper shelf of the internal surface and the lower rib of the boot. The pivoting member has a pivoting axis lying within an imaginary plane disposed perpendicular to the centerline of the well. The pivoting member engages the locking face limiting axial movement of the boot with respect to the internal surface and thereby preventing disengagement of the boot from the spark plug.
A feature of the present invention is the ability to determine when a boot is fully seated on a spark plug disposed within a spark plug well.
Another feature of the invention is providing a secondary means, other than the ignition wire terminal clip snap fit engagement to the spark plug, which secures the boot to the spark plug.
Yet another feature of the invention is reduced warranty costs by eliminating unintentional unseating of the boot from the spark plug and by providing a more robust electrical connection design.